161878169 has 2 divisors, whose sum is σ = 161878170. Its totient is φ = 161878168.

The previous prime is 161878139. The next prime is 161878181. The reversal of 161878169 is 961878161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 88604569 + 73273600 = 9413^2 + 8560^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161878169 is a prime.

It is a super-2 number, since 2×161878169² = 52409083197585122, which contains 22 as substring.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (161878109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80939084 + 80939085.

It is an arithmetic number, because the mean of its divisors is an integer number (80939085).

Almost surely, 2^161878169 is an apocalyptic number.

It is an amenable number.

161878169 is a deficient number, since it is larger than the sum of its proper divisors (1).

161878169 is an equidigital number, since it uses as much as digits as its factorization.

161878169 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 47.

The square root of 161878169 is about 12723.1351875236. The cubic root of 161878169 is about 544.9994882581. Note that the first 3 decimals are identical.

The spelling of 161878169 in words is "one hundred sixty-one million, eight hundred seventy-eight thousand, one hundred sixty-nine".